Suitable timber for long term water immersion?

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jonboy

27 posts

Geek

#140993 26-Feb-2014 13:37

I am going to be building a small dam on a farm (approx 1-1.5m high) to return a boggy old creek back to the small lake that it used to be. I'm considering using some square timber planks stacked on top of each other with the ends buried a good length into either side of the stream.

Can anyone recommend a suitable timber to use that wont rot or degrade or any other suitable material/construction methods?

timmmay

20589 posts

Uber Geek

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#994826 26-Feb-2014 13:40

H6 treated.

mattwnz

20165 posts

Uber Geek

#994832 26-Feb-2014 13:53

Reinforced concrete would probably be the best option as you shouldn't need to worry about it needing replacing for a long time. Also no leeching of chemicals from the timber into the water.

Coil

6614 posts

Uber Geek
Inactive user

#994843 26-Feb-2014 14:04

Built one myself 10 years ago out of fence posts and still holding strong.

jonboy

27 posts

Geek

#994857 26-Feb-2014 14:26

mattwnz: Reinforced concrete would probably be the best option as you shouldn't need to worry about it needing replacing for a long time. Also no leeching of chemicals from the timber into the water.

I did think about concrete but access is not great so hauling heavy concrete posts or pouring a wall in place is out of the question. Saying that, I would prefer to avoid heavily treated timber so I'm not adding more pollution to our rivers.

nickb800

2721 posts

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Trusted

#994897 26-Feb-2014 15:21

Do make sure that what you're doing is compatible with relevant district/regional plans under the RMA otherwise you could be liable to be prosecuted. Just because it is 'improving' the waterway, doesn't necessarily mean that it won't need consent.

You've probably already thought of this, but just thought I'd point it out because penalties under the act can be massive

NotReally

75 posts

Master Geek

#994909 26-Feb-2014 15:41

H6 treated timber uses a fixed preservative and won't leach even in running water. The timber won't pollute the stream and will last at least 50 years so it (probably) won't be you rebuilding it. :)

blackjack17

1705 posts

Uber Geek

#994912 26-Feb-2014 15:46

The timber will only rot where it is exposed to air, if it entirely encased underwater or soil, most timber is good for a surprising long period of time.

That being said is an earthen dam out of the question?

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